The second pillar of Islam is the religious duty to perform five prescribed daily prayers or salat. All adult Muslims are supposed to perform five prayers, preceded by ritual cleansing or purification of the body at different intervals of the day. The Qur'anic references also mention the acts of standing, bowing, and prostrating during prayers and facing a set direction, known as qibla. The Muslims were first required to face Jerusalem during prayer, but already during Muhammad's lifetime they were commanded to face the Kaaba, an ancient shrine in the city of Mecca. The Qur'an also refers to the recitation of parts of the Qur'an as a form of prayer. However, even with its numerous references, the Qur'an alone does not give exact instructions for this central ritual of prayer.

The most detailed descriptions of the rituals for prayer derive from the example set by the prophet Muhammad and are preserved in later Islamic traditions. Some details of these rituals vary, however all Muslims agree that there are five required daily prayers to be performed at certain times of day: dawn ( fajr or subh), noon (zuhr), midafternoon (asr), sunset (maghrib), and evening (isha). The dawn, noon, and sunset prayers do not start exactly at dawn, noon, and sunset; instead, they begin just after, to distinguish the Islamic ritual from earlier pagan practices of worshiping the sun when it rises or sets.

A prayer is made up of a sequence of units called bowings (rak'as). During each of these units, the worshiper stands, bows, kneels, and prostrates while reciting verses from the Qur'an as well as other prayer formulas. With some variations among different Muslim sects, at noon, afternoon, and evening prayers, these units are repeated four times, while during the sunset prayer they are repeated three times, and at dawn only twice. The opening chapter of the Qur'an, al-Fatiha, is repeated in each unit in a prayer sequence. Each prayer concludes with the recitation of the profession of faith followed by the greeting "may the peace, mercy, and blessings of God be upon you."

Wherever Muslims live in substantial numbers throughout the world, the call to prayer, or adhan, is repeated five times a day by a muezzin (crier) from a mosque, the Muslim place of worship. Muslims are encouraged to pray together in mosques, but group prayer is only a religious obligation for the noon prayer on Friday. Women, travelers, sick Muslims, and those attending to the sick are granted license not to attend the Friday congregational prayer, although they may attend if they wish.

The Friday noon prayer is led by an imam, who is simply a prayer leader; this prayer differs from the usual noon prayers of the other days of the week. As a required part of the ritual at this congregational meeting, two sermons precede the prayer. On other days, Muslims can pray anywhere they wish, either individually or in groups. They must observe the rituals of praying at certain times of day, facing in the direction of Mecca, observing the proper order of prayers, and preparing through symbolic purification. Depending on the situation, this last ritual of ablution requires either total washing of the body or a less elaborate ritual washing of the hands, mouth, face, and feet.

In addition to the five required daily prayers, Muslims can perform non-obligatory prayers, some of which have fixed ritual formats and are performed before or after each of the five daily prayers. Others are performed at night, either individually or with other Muslims. These additional formal and informal prayers give expression to the primary function of prayer in Islam, which is personal communication with God for the purpose of maintaining the abiding presence of the divine in the personal lives of Muslims. The more formal aspects of prayer also serve to provide a disciplined rhythm that structures the day and fosters a sense of community and shared identity among Muslims.